2023-12-26-亚开行-评估全球净零转型对亚洲发展中国家的影响_综合评估模型的启示_58页_3mb

Summary of "Assessing the Implications of a Global Net-Zero Transition for Developing Asia: Insights from Integrated Assessment Modeling"

Core Content

This working paper from the Asian Development Bank (ADB) examines the implications of a global net-zero transition for developing Asia using a global integrated assessment model (IAM). It evaluates different climate policy scenarios to understand how developing Asia can transition to low-carbon growth while addressing the region's role as a major contributor to global carbon emissions.

Main Viewpoints

• Developing Asia's Role in Emissions: Developing Asia is the world's fastest-growing source of carbon emissions, contributing 44% of global greenhouse gas (GHG) emissions in 2019. Its per capita emissions remain lower than the global average, but its population and economic growth pose significant future climate risks.

• Climate Vulnerability: The region is highly vulnerable to climate change due to its geographic exposure to extreme weather events and limited socioeconomic development. This vulnerability underscores the urgency of effective climate policies.

• Current Policies and NDCs: National net-zero pledges do not provide a high probability of keeping global warming below 2°C. Current policies and NDC efforts are insufficient to meet the Paris Agreement goals, leading to a projected mean warming of 2.4°C by 2100.

• Efficient Decarbonization Pathways: A coordinated global approach to climate policy, such as a global carbon market, is essential to achieve the Paris Agreement targets. Under such scenarios, emissions can be significantly reduced, with a global carbon budget of 1,150 GtCO₂.

• Regional Impacts: The transition to net-zero emissions would lead to substantial climate benefits, including a 3-fold benefit-cost ratio, improved air quality, and health gains. These benefits are most pronounced in the lowest-income subregions of Asia.

• Energy Sector Transformation: The energy sector is the largest contributor to emissions in developing Asia, accounting for nearly 75% of GHG emissions. Decarbonization of the power sector is critical, with coal expected to drop from ~50% of primary energy in 2020 to ~13% by 2050 under the accelerated global net-zero scenario. Renewable energy sources, particularly solar and wind, will dominate electricity supply by 2040.

• Land Use and Agriculture: Land use and agriculture are important sources of emissions, especially in Southeast Asia and the Pacific. Under the most stringent scenarios, there is a significant increase in forest cover, with about 95 million hectares added by 2050. Land use changes will also play a key role in mitigation, particularly through bioenergy crops.

• Socioeconomic Implications: The transition to net-zero will bring energy-related employment increases, but it will also require policies to support disadvantaged groups and ensure equitable outcomes.

Key Information

• Five Scenarios Analyzed:

  1. Current Policies: Emissions reach 3,270 GtCO₂ by 2100, leading to a mean warming of 3.0°C.
  2. NDC Effort: Emissions reach 2,650 GtCO₂ by 2100, with mean warming of 2.4°C.
  3. Uncoordinated Net-Zero: Emissions drop to 1,420 GtCO₂ by 2100, with a 50% chance of staying below 2°C.
  4. Global Net-Zero: Emissions reach 1,150 GtCO₂ by 2100, with a high probability of meeting the 2°C target.
  5. Accelerated Global Net-Zero: Emissions reach 1,150 GtCO₂ by 2100, with earlier and more efficient mitigation, leading to a smoother transition.

• Modeling Approach: The WITCH model is used to simulate the economic and environmental impacts of different climate policy pathways. It incorporates energy system transitions, land use changes, and climate and economic variables.

• Key Findings:

  • Climate benefits outweigh costs by a factor of 3.
  • Air quality improvements could save 0.35 million lives by 2050.
  • Energy-related employment is expected to rise.
  • The transition to clean energy is more dramatic in the electricity sector than in other areas.
  • Carbon capture and storage (CCS) and bioenergy with CCS (BECCS) are important for long-term mitigation, especially in economies reliant on fossil fuels.

• Challenges and Policy Needs:

  • Current NDCs and net-zero pledges are not sufficient.
  • A global carbon market is necessary to improve the economic efficiency of climate policy.
  • Appropriate policies are required to address potential negative impacts on vulnerable populations.

Conclusion

The paper emphasizes that while developing Asia is a significant emitter and highly vulnerable to climate change, a global net-zero transition offers substantial benefits. However, achieving this transition requires stronger global cooperation, coordinated policy efforts, and consideration of socioeconomic impacts to ensure fairness and effectiveness.